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Predicting our future

19 March 2004

While the debate about whether human activity impacts on climate grows less controversial, predicting the extent of those changes and deciding the political means to mitigate their impact, remain highly contentious. This is science at its most difficult.

At the heart of the public debate is the mismatch between the wish to limit environmental damage both locally and globally and the price that the individual is prepared to, or capable of, paying. Politicians, the media and the public are demanding explanations of what is happening, while business requires predictions for the future to be well founded and robust to ensure long-term fiscal stability within which they can plan. This is science at its most difficult with political pressure at its back, scare-mongering rife in the press, and a growing feeling of public unease that inaction could mean that any environmental damage inflicted now, may be impossible to rectify later.

The University is responding to these issues in a number of different ways. For example, it has recently launched BRIDGE, the Bristol Research Initiative for the Dynamic Global Environment. In the context of UK research, its remit is uniquely wide. It aims to increase our understanding of the causes of climate change by testing and developing the computer models used to predict future climate, and to assess the impacts on all aspects of human society. The research will focus on the emerging area of ‘Earth System Science’, which looks at the complex interactions between all the Earth’s components: the oceans, atmosphere, ice sheets and biosphere, as well as human activity.

The remit of BRIDGE is unique

‘By taking this whole systems approach, we are more likely to find sustainable solutions to environmental problems,’ says Professor Paul Valdes who heads BRIDGE and is based in the School of Geographical Sciences. A mathematical-physicist-turned meteorologist, with a research background in past climates, Valdes stresses the importance of bringing together experts from across the University to help develop our understanding of environmental processes and improve our ability to predict future changes. ‘Predictions of future climate are a critical component of the data that policy-makers use to come to decisions on how to respond to climate change. To ensure that the models generating these predictions are as accurate as possible, we run them for particular periods in the past when we know what the climatic conditions were like. If the computer model can simulate those conditions accurately then we can have some confidence in its predictions for the future.’

As well as running climate models in the past, the group also runs predictive simulations and examines just how far it is possible to redress the environmental change brought about by human activity. For example, scientists currently think that rising temperatures caused by the emission of large quantities of greenhouse gases are melting the Greenland ice sheet (see re:search 5).

A recent experiment therefore examined what would happen if the ice sheet melted completely, which models suggest would take about 2,000 years, and Greenland then experienced cooling as a result of a reduction in greenhouse gas emissions. As the figures illustrate, the model does predict a partial re-growth of the ice-sheet over a further 2,000 years, but not to its present-day dimensions. While this initial study is far from complete, it does raise the worrying possibility that some of the changes humans are making to the earth system may have irreversible consequences.

BRIDGE is also beginning to develop research on how climate has influenced human activity in the past. John Hughes is involved in examining the impact of a changing climate on hominid evolution and dispersal: ‘Our contribution to this project is to model the climate from two million years ago to 20,000 years ago. This spans the time period from when the oldest hominids found so far as fossils were living in the African Rift Valley, to when humans were well established as the only global species living in every environment from tropical beach to icy tundra. Vegetation, ice distribution and land bridges resulting from sea level fall must all have had impacts on where hominids migrated to and how big their populations could be. Comparison of these environmental models with our models of hominid dispersal patterns will help us understand just how important climate factors were in the past.’

QUEST is a fantastic opportunity to tackle some of the tricky questions

The appointment of Professor Colin Prentice to the Department of Earth Sciences is a further boost to climate change research in Bristol. He is to lead NERC’s £13 million research initiative entitled QUEST – Quantifying and Understanding the Earth System. Professor Prentice said, ‘QUEST is a fantastic opportunity to tackle some of the tricky questions like what’s going to happen to the carbon we are putting into the atmosphere as the climate changes; what are the potential effects of global warming on human activities; and what has controlled the Earth’s atmospheric composition naturally – things we need to understand far better if we are really to make sense of what’s happening to the Earth today.’

Bristol researchers are also responding to many other aspects of environmental change. For instance, the biogeochemistry  laboratories have just been refurbished to the tune of £2 million, facilitating the biogeochemists to improve our understanding of the global carbon cycle, including the controls on greenhouse gas concentrations, and the atmospheric chemists to measure and model the effects of pollutants.  In addition, the hydrologists and civil engineers are developing European flood forecasting and flood risk management systems, and research in economics and sustainability is helping to decide policies to adapt and mitigate the impact of climate change.

These are just a few examples of the exciting new challenges faced by Earth System scientists. It is a diverse research area requiring interdisciplinary input to respond coherently to the growing concerns about environmental change. The University recognises this and with substantial investment has ensured that Bristol will make a difference.

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